The present invention relates generally to the field of electric motors and methods and apparatus for manufacturing electric motors. More particularly, the invention relates to a novel technique for manufacturing motors that may be machine wound.
Electric motors of various types are omnipresent in industrial, commercial and consumer settings. In industry, such motors are employed to power all types of rotating machinery, such as pumps, conveyors, compressors, fans and so forth, to mention only a few. Conventional alternating current electric motors may be constructed for single or multiple phase operation, and are typically specifically designed to operate at predetermined synchronous speeds, such as 3600 rpm, 1800 rpm, 1200 rpm and so on. Such motors generally include a stator, comprising a multiplicity of coils, surrounding a rotor, which is supported by bearings for rotation in the motor frame. In the case of AC motors, alternating current power applied to the motor causes the rotor to rotate within the stator at a speed which is a function of the frequency of alternating current input power and of the motor design (i.e., the number of poles defined by the motor windings and rotor resistance). In DC motors power is similarly applied, and the speed of the motor may be controlled in a variety of manners. In both cases, however, a rotor shaft extends through the motor housing and is connected to elements of the machinery driven by the electric motor.
In conventional electric motors, conductors, known as stator windings, are routed through parallel slots formed around the inner periphery of a metallic core. The stator windings are electrically connected in groups around the stator core to form electro-magnetic coils. The coils establish the desired electro-magnetic fields used to induce rotation of the rotor. The number and locations of the windings in the stator core generally depends upon the design of the motor (e.g., the number of poles, the number of stator slots, the number of winding groups, and so forth). Each winding coil includes a number of turns of wire that loop around end or head regions of the stator between the slots in which the winding coil is installed. Multiple conductors are wound in each slot in a randomly wound stator. Following installation in the slots, the coils in each group are generally pressed into a bundle at either end of the stator. The stator windings are connected to electrical wiring that is routed from the stator to a wiring or conduit box located either within the motor frame or on the outside of the motor through corresponding holes in the motor frame and the conduit box.
The process for installing the coils within the stator generally includes inserting the coils, lacing the coils, and forming the coils into bundles, which may be referred to as winding the stator. Each of these processes may be completed by hand as a manual process or by machine as an automated process. The insertion process typically involves guiding the coil or coils into a slot and pulling the coil through the entire length of the slot. After pulling the coil through the slot, the coil may be redirected and pulled through the entire length of another slot. Once the coils are inserted into the slots, a lacing process may be utilized to wrap string or other suitable binding material around the exposed coils at the ends of the stator. This process is used to bundle the coils together into a group. Another process that is typically used in manufacturing a motor is the forming process. In the forming process, the coils are formed into bundles that are adjusted and manipulated into specific dimensions for the motor. In addition to these processes, other processes may be used to wind the stator.
While conventional motor manufacturing equipment and methods have been generally satisfactory in many applications, they are not without drawbacks. For example, one of the approaches that may be utilized to insert coils into the stator's slots may be a hand winding process. The hand winding process typically requires numerous people to pull and guide the coils through the various slots. This type of process is more expensive because it requires a larger labor force to complete the task, which results in an increase in the cost of the motors. Another approach that is typically utilized is a machine winding process. The machine winding process requires fewer personnel and utilizes a machine to install the coils into the slots. This type of process has a lower labor cost, which reduces the associated cost of manufacturing the motor as well.
Furthermore, conventional motor manufacturing components for square motors have additional drawbacks related to the methods for assembling and winding the stator for the square frame. For example, each stator winding is typically inserted, laced, and formed by a manual process with the conventional components. Typically, at each end of the stator, an end plate is attached as part of or to the metallic core. Conventional end plates for a square motor generally extend beyond the end of the slots within the metallic core. The portion of the endplate that extends beyond the slots hinders automated winding processes for the motor. Thus, the motor is typically hand wound, due to the over-extending end plate.
Moreover, conventional techniques for manufacturing a motor have additional drawbacks with regard to the winding process. Generally, a slot within the metallic core includes a slot liner that is used for various purposes. For instance, the slot liner may extend beyond the end of a slot to provide insulation and prevent short circuits. However, the slot liners may be damaged during the winding process. Thus, a support is often required during the winding process to prevent the slot liners from being damaged. Conventional methods utilize a cuff support tool, which is attached to the end of the motor for the winding process and is later removed. This additional tool is undesirable and increases the time to manufacture and cost associated with manufacturing the motor.
There is a need, therefore, for an improved technique in forming a stator of an electric motor, generator, or other machine to enable automated winding. There is a particular need for a technique that provides the components and/or a method for automatically assembling and automatically winding an electric motor during the electric motor manufacturing process.